1. Technical Field
The present invention relates to elimination of wiggle noise in a disk drive storage device using a magnetic thin film head, and more particularly a method for eliminating wiggle noise generated from a magnetic thin film head of a disk drive storage device during retrieving servo information of a servo sector after writing data in such a disk drive storage device.
2. Related Art
Disk drive storage devices such as hard disk drives (HDDs) and floppy disk drives (FDDs) are widely used as auxiliary memory devices for computer systems. In particular, HDDs are commonly used to store a large quantity of data as well as to provide high speed access to stored data in computer systems. In order to maximize data storage capacity of a HDD, the track density of the disk (TPI) must be increased, and the transducer head must also be highly reliable.
One common type of highly reliable transducer heads is a thin-film head having a core formed by employing semiconductor fabrication technology as disclosed, for example, in U.S. Pat. No. 4,727,643 for Method For Manufacturing A Magnetic Head By A Thin Film Technique issued to Schewe et al., U.S. Pat. No. 5,025,342 for Thin-Film Magnetic Head Device For Recording And Reproducing issued to Nagata et al., U.S. Pat. No. 5,132,859 for Thin Film Structures For Magnetic Recording Heads issued to Andricacos et al., U.S. Pat. No. 5,187,860 for Method Of Manufacturing Thin Film Magnetic Head issued to Horibata et al., U.S. Pat. No. 5,245,493 for Magnetic Information Storage Apparatus Including Magnetic Head And Method For Making Magnetic Head issued to Kawabe et al., and U.S. Pat. No. 5,373,408 for Configuring Domain Pattern In Thin Films Of Magnetic Heads issued to Bischoff et al. Other types of transducer head with high disk density are disclosed, for example, in U.S. Pat. No. 5,623,378 for Signal Reproducing Circuit Adopted For Head Utilizing Magneto-Resistive Effect With Control For Reducing Transient Period Between Read And Write States issued to Shibasaki. Generally, a thin-film transducer head may increase data write density, but experiences various problems relating to electrical characteristics of the head poles. A typical problem relating to the electrical characteristics of the head poles is the so-called wiggle noise which is noise generated due to variation of a magnetic field when the HDD is switched from a data write operation to a data read operation. This type of noise often interferes with the retrieval of correct information (servo information or data information). In addition, if the wiggle noise is so severe that servo information cannot be retrieved, servo control cannot be performed. Moreover, if the wiggle noise is generated with the thin-film head ("head") shifting to a servo sector after writing data in a data sector, the servo address mark is not normally detected during a servo address mark interval, and the head must be moved to a parking zone (or spare sector) to perform a dummy write operation, and then retrieve servo information from the servo sector of the track. If the head must move to the parking zone or spare sector (PAD between sectors) to eliminate the wiggle noise which occurs during retrieving the servo information, the time for accessing data is undesirably delayed, and thereby degrading the overall performance of the disk drive.